The entire disclosure of Japanese Patent Application No. 2000-196977 filed on Jun. 29, 2000 including specification, claims, drawings and summary are incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a method for instructing target positions for mobile bodies, a method for controlling transfer thereof, and a method as well as a system of optical guidance therefor, and more particularly to a method for instructing target positions for mobile bodies, a method for controlling transfer thereof, and a method as well as a system of optical guidance therefor, all of which are suitably used in the case where mobile bodies such as wheeled or walking mobile robots are guided.
2. Description of the Related Art
In general, a mobile body such as an autonomous omni-directional mobile robot has been known as a mobile body being movable in a given environment.
Incidentally in case of transfer in such mobile body, it is required to specify a position of coordinates of the mobile body in question in an environment wherein the mobile body can be transferred in order to set a position that is a target to be determined as its goal by the mobile body in question (hereinafter referred to as xe2x80x9ctarget positionxe2x80x9d). The actual position of coordinates of a mobile body can be generally determined on the basis of dead-reckoning, for example such as from the odometry data of the mobile body.
However, when a position of coordinates is determined only based on the dead-reckoning data of a mobile body, there has been such problem that errors defined between the position of coordinates in the mobile body determined on the basis of the dead-reckoning data of the mobile body and a position of coordinates on which the mobile body resides in reality are accumulated, because of a limit in precision for working traveling wheels or legs in the mobile body and slippage (running idle) of such traveling wheels or legs in the case when the mobile body travels in a given environment.
For this reason, it has been necessary for compensating a position of coordinates obtained on the basis of the dead-reckoning data of a mobile body by the use of either means for functioning as sensors such as sonar, gyroscope, and camera, or land-marks in a given environment in order to specify correctly a position where the mobile body resides actually in the environment.
On the other hand, known methods of motion control of a mobile body in an environment rely on, for example, a common coordinate system wherein positions of coordinates of mobile bodies in the environment and environmental objects are computed, and the respective positions of coordinates obtained as a result of the computation are represented in an environmental model indicating the environment thereof.
In this case, it is required that the newest positions of coordinates are to be supplied always into the environmental model to acquire the newest position of a mobile body in the environment.
As described above, however, there are errors each of which exists between a position of coordinates of a mobile body determined on the basis of dead-reckoning data of the mobile body in question and a position of coordinates of the mobile body where the mobile body resides actually, and such errors are accumulated with travel of the mobile body, so that a discrepancy between the actual position of the mobile body in the environment and its computed one in the environment model increases over travel time and becomes substantial.
In this respect, if target positions towards which the mobile body is to be transferred are set on the basis of coordinate positions of the mobile body in the environmental model, which do not correspond to that of the mobile body residing actually in the environment, there has been such a problem that it results in unexpected dangerous motion of the mobile body in the environment.
Accordingly, to exclude such unexpected dangerous motion of the mobile body in the environment in the case when target positions towards which the mobile body is to be transferred in the environment, the above-described discrepancy (the discrepancy between the actual position of the mobile body in the environment and its computed coordinate positions in the environment model must be compensated).
The above-described problem can be eliminated if a target position is indicated in the environment and its numerical coordinates are implicitly transmitted to the mobile body, which detects the indicated target positions and evaluates its relative coordinates by means of a visual feedback. In this case, a transformation between the common coordinate system and the mobile body""s coordinate system becomes less relevant or is not even required, and the above-described discrepancy is compensated by means of visual feedback.
A variety of manners has been proposed heretofore as methods for guiding mobile bodies.
Namely, U.S. Pat. No. 5,622,236 discloses to draw a guidance line on a floor surface, or U.S. Pat. No. 4,947,094 discloses to draw a guidance line on a ceiling. Furthermore, it is disclosed by U.S. Pat. No. 5,815,825 to use magnetic markers in a floor surface. Moreover, it is disclosed by U.S. Pat. Nos. 4,773,018 and 4,858,132 to track a stationary light source.
Besides, a vehicle guidance by means of a laser beam is proposed and disclosed in U.S. Pat. No. 5,285,205 wherein a stationary laser indicates a path direction to a human operator situated inside the vehicle, and concerning this method, see also U.S. Pat. No. 4,856,896.
Further, a scanning laser mounted on a vehicle is proposed and disclosed in U.S. Pat. No. 4,790,402 wherein the laser serves as a transmitter-receiver to measure relative distances to the surrounding objects.
Moreover, reflective beacons in the environment are proposed in U.S. Pat. Nos. 4,855,915, 4,846,297, and 4,817,000.
Besides, indication of a target by means of projection of laser light onto the target where it forms a light dot (spot) is known, for instance, in a field of weapons. Namely, a device to adjust the laser optical axis with the axis of the weapon is proposed in U.S. Pat. No. 4,916,713.
The present invention has been made in view of the prior art as described above, and an object of the invention is to provide method for instructing target positions for mobile bodies wherein target positions in the case where the mobile bodies such as mobile robots can be instructed, a method for controlling movements thereof, and a method as well as a system of optical guidance therefor in accordance with a manner different from the prior art as described above.
Furthermore, another object of the present invention is to provide a method for instructing target positions for mobile bodies, which is used suitably in the case where the mobile bodies set target positions towards which the respective mobile bodies are to be transferred in an environment where a number of the mobile bodies such as mobile robots reside, a method for controlling transfer thereof, and a method as well as a system of optical guidance therefor.
Besides, another object of the present invention is to provide a method for instructing target positions for mobile bodies, which is used suitably in the case where a human being sets target positions towards which the mobile bodies are to be transferred in an environment where a number of the mobile bodies such as mobile robots reside, a method for controlling transfer thereof, and a method as well as a system of optical guidance therefor.
In order to achieve the above-described objects, a method for instructing target positions of at least one or more of mobile bodies contained movably in a predetermined environment according to the present invention comprises light beacons being produced by a light beam projecting device in a surface on which the mobile bodies are to be transferred, whereby target positions towards which the mobile bodies are to be transferred being instructed.
According to the present invention one mobile body can instruct target positions towards which another mobile body is to be transferred. For instance, it is possible to notify target positions towards which a specified mobile body of a number of mobile bodies in an environment is to be transferred.
In this respect, when light beacons are produced in a surface on which mobile bodies are to be transferred by projecting a light beam from a light beam projecting device, target positions may be appointed on a map in a display by clicking a mouse through a user interface with a user (human being) or by the like manner, and the light beam is projected onto the very positions, or it is possible to project the light beam onto the positions by means of a light beam projecting device which is remotely operated, for example through a network by another computer, the other mobile bodies or a human being.
Moreover, an example of the light beam-projecting device includes laser pointer, LED, mercury lamp, fluorescent lamp and other sources of focused light.
In this case, a laser pointer may be mounted on a predetermined place such as a ceiling, or a compact laser pointer, which can be held by a user (human being) and may change freely at hand a position onto which a light beam is to be projected may be employed.
Besides, a mobile body may be equipped with a laser pointer to indicate target positions for the other mobile bodies.
Furthermore, a method for controlling mobile bodies according to the present invention comprises the light beacons produced in the above-described surface on which the mobile bodies are to be transferred being detected by the use of a visual device of a mobile body mounted thereon, and a relative positional relationship between the target positions represented by the light beacons and a present position of the mobile body in question being computed by means of image data processing or signal processing, whereby the mobile body in question being controlled so as to transfer towards the light beacons produced in the above-described surface on which the mobile bodies are to be transferred.
In this case, for example, a charge coupled device (CCD) camera or a position sensing device (PSD) camera and the like may be used as the above-described visual device.
Furthermore, an optical guidance method for mobile bodies according to the present invention comprises target positions being instructed with respect to a predetermined mobile body while using the above-described light beam-projecting device, whereby the mobile body being guided to the target positions.
In this case, the above-described instruction for target positions is implemented by means of a user (human being), another computer, the other mobile bodies or the like.
Moreover, in the present invention, a light beam is used to project the same, whereby the light beacons, which are obtained by lighting on or lighting off only or are obtained by lighting a light beam having a predetermined features (i.e., colors of lights, shapes of areas lighting on, brightness of areas lighting on, manners of lighting on such as methods of blinking light beams, patterns of blinking light beams and so on), are produced on the surface on which mobile bodies are to be transferred in an environment, the resulting light beacons are used as target positions, the mobile bodies detect the light beacons (dots, spots) indicated as the target positions to specify relative coordinate positions defined between the light beacons (dots, spots) and the mobile bodies, thereby obtaining revised target positions.
In this case, if visual feedback is utilized in the case where target positions represented by light beacons having predetermined features (i.e., colors of lights, shapes of areas lighting on, brightness of areas lighting on, manners of lighting on such as methods of blinking light beams, patterns of blinking light beams and so on) on a surface on which mobile bodies are to be transferred are detected to specify them, a degree of accuracy in positioning of the mobile bodies in an environment can be elevated.
Besides, in case of updating positions of mobile bodies in an environmental model, when positions at which the mobile bodies exist actually in the environment are specified, a degree of precision in the updating can be elevated.
Namely, an optical guidance system for at least one or more of mobile bodies contained movably in a predetermined environment according to the present invention comprises a target position optically instructing means composed of a light beam projecting means for projecting a light beam having a predetermined color or other features in a desired region on a predetermined surface on which the mobile bodies are to be transferred to produce the predetermined colored beacons (dots, spots) in the desired region on the above-described predetermined surface, whereby the target positions towards which the mobile bodies are to be transferred are indicated; and a light beam projection control means for controlling operations of lighting up/lighting out in the above-described light beam projecting means, whereby starting/stopping projection of light beam on the above-described predetermined surface is controlled, besides an optical axis of the light beam projected from the above-described light beam projecting means is directed to a desired position on the above-described predetermined surface; a detection specifying means composed of a detection means for detecting the predetermined colored light beacons (dots, spots) produced on the above-described predetermined surface by means of a visual device; and a relative position specifying means for producing relative positional information, which indicates a relative position by specifying the relative position in question defined between the predetermined light beacons (dots, spots) that is an object to be detected by the above-described detection means and each of the mobile bodies in accordance with the results detected by the above-described detection means; and a transfer control means for controlling the mobile body, target positions of which have been indicated by means of the light beacons (dots, spots) derived from the above-described target position instructing means, so as to transfer towards the target positions on the basis of the relative positional information produced by the above-described relative position specifying means.
In this case, for example, a CCD or PSD camera, an optical sensor or the like may be used as the visual device.
In the present invention, the at least one or more of mobile bodies that are movable in a predetermined environment are equipped with the above-described detection specifying means, respectively.
Further, in the present invention, the above-described light beam projecting means is fixed at a predetermined position.
Moreover, in the present invention, a mobile body is equipped with the above-described light beam projecting means.
Besides, in the present invention, the above-described light beam projecting means is equipped with a robot manipulator, and the above-described light beam projection control means controls the above-described robot manipulator thereby directing an optical axis of the light beam projected from the above-described light beam projecting means to a desired position in the above-described predetermined surface on which the mobile bodies are to be transferred.
Besides, in the present invention, the above-described light beam projecting means is hand-held by a human operator who controls the described light beam projecting means and directs an optical axis of the light beam to a desired position in the surface on which the mobile bodies are to be transferred.
In addition, in the present invention, the above-described light beam projection control means controls the above-described light beam projecting means on the basis of information obtained through a network.
Furthermore, an optical guidance system for at least one or more of mobile bodies contained movably in a predetermined environment according to the present invention comprises a light beam projecting means for projecting a light beam having a predetermined color or other features in a desired region on a predetermined surface on which the mobile bodies are to be transferred to produce the predetermined light beacons in the desired region on the above-described predetermined surface, whereby the target positions towards which the mobile bodies are to be transferred are indicated, the above-described light beam projecting means being held by a human being and an optical axis of the light beam being directed to a desired position in the above-described predetermined surface by means of operations of the human being; a detection specifying means composed of a detection means for detecting the predetermined light beacons produced on the above-described predetermined surface by means of a visual device; and a relative position specifying means for producing relative positional information, which indicates a relative position by specifying the relative position in question defined between the predetermined light beacons that is an object to be detected by the above-described detection means and each of the mobile bodies in accordance with the results detected by the above-described detection means; and a transfer control means for controlling the mobile body, target positions of which have been indicated by means of the light beacons derived from a target position instructing means, so as to transfer towards the target positions on the basis of the relative positional information produced by the above-described relative position specifying means.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.